Effect of Nd–Co substitution on magnetic and microwave absorption properties of SrFe12O19 hexaferrites

Nd–Co-substituted M-type strontium hexaferrites were prepared by sol–gel-autocombustion method. Crystalline structure, morphology, magnetic properties, and microwave absorption properties of Sr1−xNdxFe12−xCoxO19 (x = 0–0.4) were studied via X-ray diffraction, scanning electron microscope, vibrating sample magnetometer, and vector network analyzer, respectively. Single-phase M-type strontium hexaferrites, with a chemical composition of Sr1−xNdxFe12−xCoxO19 (x = 0–0.3), were formed by being heated at 1200 ˚C for 3 h in air. Saturation magnetization and coercivity reached a maximum at x = 0.2. For samples with x = 0.2, a minimum reflection loss of −22 dB was obtained at 16.2 GHz for a layer of 1.9 mm in thickness. The reflection loss of Sr0.8Nd0.2Fe11.8Co0.2O19 ferrite (1.5–3.0 mm in thickness) is less than −10 dB over the range of 9.8–18 GHz. It indicates that the substituted Nd–Co can greatly improve the microwave absorption properties of SrFe12O19 hexaferrites.

► Nd–Co doped Sr12Fe1O19 were prepared by sol–gel-autocombustion method. ► Single lattice structure of strontium ferrite can be obtained when x ≤ 0.3. ► The grain size of particles decreased with increase in x value. ► Nd–Co doped Sr12Fe1O19 have a prominent effect magnetic and absorption characteristics. ► Sr0.8La0.2Fe11.8Co0.2O19 powders exhibit excellent microwave absorption properties.